This chair concept has been refined in US Patent Disclosure US-A 2004/0183348. This reference discloses a support element, corresponding to the structural part described above, which has a skeleton that has a skin to which a plurality of ribs are pivotably connected. The skin forms a flexible load-bearing face for supporting a seating force that is exerted on the skin by a body. The skeleton works together in such a way that it is at least partly deformed by the seating force counter to the direction of the seating force. The skeleton furthermore has at least one spring element, which joins the skin and/or ribs together, or the skin in one piece forms a backrest and a seat face. The spring force of the spring element in particular brings about an adaptation of the shape of the support element. For this purpose, the spring element is located in a diagonal of the rectangle that is defined by two ribs and the skin located at two ends of the ribs.
Such chair backrests have the advantage that the backrest adapts to the form of the thoracic spine with a concave deformation and at the same time supports the thoracic spine at every point. The adaptation in the concave region of the backrest takes place because of the shape of the back being braced and because of the forces exerted by it on the backrest.
A disadvantage of these chair backrests, however, is that the chair backrest has vertical sections that remain the same over its entire width.
It is therefore the object of the invention to create a support element which is equipped with a support structure that optimally conforms to the body in response to the shape of the body and to pressure forces exerted on the support element by the body being braced and supports the body. The support face, in a preferred embodiment of the invention, should also be adapted to the shape of the back transversely to the length of the spinal column and of the support element as well.